Cutting tool for rough and finish milling

ABSTRACT

A milling cutter comprises a cutter body having at least two operational annular rings. An outer ring is provided for rough milling and includes a plurality of cutting inserts spaced about the periphery of the cutter body. Positioned radially inward of the outer ring is at least one inner finish ring. The finish ring comprises a coating of abrasive material. As a result, a workpiece can be both rough and finish milled by a single milling cutter with the rough cutting inserts and the abrasive material.

CROSS REFERENCE To RELATED APPLICATIONS

[0001] This application is a Continuation-In-Part of copending U.S.application Ser. No. 10/234,220, entitled “Cutting Tool for Rough andFinish Milling,” the entire contents of which are incorporated herein byreference.

FIELD OF THE INVENTION

[0002] This invention generally relates to cutting tools. Moreparticularly, this invention relates to a single milling cutter capableof performing both rough and finish milling operations.

BACKGROUND OF THE INVENTION

[0003] Milling cutters for rough milling operations are well known. Suchmilling cutters typically comprise a cutter body, which is a generallycircular shaped ring, having a plurality of pockets in an outerperiphery thereof. A cutting insert is secured in each pocket. Eachcutting insert comprises a body and at least one cutting edge. The bodyis secured directly in the pocket or to an adjustable insert assembly,which is secured in the pocket. Similar milling cutters are known forfinish milling operations. Such milling cutters have an abrasivematerial thereon, instead of having cutting inserts secured thereto. Formilling a workpiece, the two milling cutters are used successively.After milling the workpiece with a rough milling cutter, the roughmilling cutter is replaced with the finish milling cutter. Replacing therough milling cutter with the finish milling cutter is a burdensome,time-consuming task.

[0004] What is needed is a single milling tool that is capable of roughand finish milling during a single operation. Ideally, such a tool wouldinclude a cutter body having a plurality of cutting inserts releasablysecured to an outer periphery thereof for rough milling purposes and anabrasive material, like diamond or cubic boron nitride (CBN), secured toa face thereof for finish milling purposes. By placing the abrasivematerial deeper into the workpiece from the cutter body than the cuttinginserts, rough and finish milling operations can be accomplished duringa single milling operation.

SUMMARY OF THE INVENTION

[0005] Generally speaking, the invention is directed to a cutting toolfor rough and finish milling. The cutting tool is in the form of amilling cutter including a cutter body comprising at least twoconcentric annular rings. An outer ring is provided for rough millingand includes a plurality of cutting inserts spaced about the peripheryof the cutter body. The cutting inserts may or may not be equally spacedabout the periphery of the cutter body. An inner finishing ring iscomprised of an abrasive material. This material can be diamond, cubicboron nitride (CBN), or any other type of suitable abrasive material. Asa result, a workpiece can be rough and finish milled with one or morepasses by a single milling cutter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Further features of the present invention, as well as theadvantages derived therefrom, will become clear from the followingdetailed description made with reference to the drawings in which:

[0007]FIG. 1 is a perspective view of a cutting tool of the inventionthat includes a cutter body without cutting inserts and a finishingring;

[0008]FIG. 2 is an enlarged partial cutaway view in perspective of thecutter body illustrated in FIG. 1 including cutting inserts forming anouter ring; and

[0009]FIG. 3 is a perspective view of a cutting tool having a patternedabrasive surface finishing ring.

DETAILED DESCRIPTION OF THE INVENTION

[0010] With reference now to FIG. 1, wherein like numerals designatelike components throughout all of the several figures, there isillustrated a cutting tool according to a preferred embodiment of theinvention. The cutting tool illustrated is in the form of a millingcutter 10 that functions to perform both a rough milling operation and afinish milling operation. The operation may be performed in a singlepass or in two or more passes. For example, the milling cutter 10 mayfirst perform a rough milling operation on a work piece in an initialpass and then in one or more subsequent passes perform a finish millingoperation on a work piece.

[0011] The milling cutter 10 includes a cutter body 12 having at leasttwo concentric annular operational rings 13, 14. An outer ring 13, whichis defined by the outer periphery of the cutter body 12, is provided forthe rough milling operation. An inner ring, which is defined as afinishing ring 14, is provided for the finish milling operation. It willbe appreciated that the cutter body 12 may include additional innerrings 14 as desired.

[0012] The cutter body 12 has a central rearward tubular shank 12 a inwhich the end of a rotatable shaft, shaft adapter, or spindle of amilling machine (not shown) can be fitted. The tubular shank 12 a ispreferably mechanically attached to the tool. However, it is alsocontemplated that the tubular shank 12 a and the tool may be machinedfrom a single piece of steel. The tubular shank 12 a has a frustoconicalshape and is perforated at two circumferentially spaced locations.Axially aligned with the perforations are slots 26 on the end of thetubular shank 12 a. These slots 26 are designed to serve as keyways toaccept keys in the spindle to assist in transmitting torque from themilling machine to the milling cutter 10. It should be understood,however, that the present invention is not limited to the tubular shankdesign shown in FIG. 1, but includes by way of example and notlimitation other connection means for connecting the tool to a rotatingspindle.

[0013] The outer ring 13 of the cutter body 12 includes a plurality ofpockets 12 c successively defined on the outer peripheral surface of thecutter body. Each of the pockets 12 c is of a prescribed dimension toreceive a cutting insert 18.

[0014] The cutting inserts 18, for example, of high-speed steel, powdermetal, carbides or ceramics, are held respectively within the pockets 12c. Each cutting insert 18 is comprised of a body 18 a and one or morecutting edges 18 b. The cutting edges can be tipped, for example, withpolycrystalline diamond (PCD), polycrystalline cubic boron nitride(PCBN), or some other material suitable for removing material from aworkpiece. The cutting insert body 18 a also has a hole 18 c in theradial direction of the cutter body 12 to receive a fastener to securethe cutting inserts in fixed relation to the pockets 12 c. This can beaccomplished in any suitable manner well known in the art. For example,a clamp stud 20 extends through the hole 18 c the cutting insert body 18a and further into a hole (not shown) in the cutter body 12. A clampstud screw 22 is threaded into a threaded hole 12 d in the cutter body12 at an angle relative to the clamp stud 20 and into engagement withthe clamp stud 20 to hold the clamp stud 20 and the cutting insert 18 inthe pocket 12 c.

[0015] The cutting inserts 18 are preferably adjustable relative to thecutter body 12. This can be accomplished in any suitable manner.

[0016] For example, adjustment elements 24 can be supported about theperiphery of the cutter body 12, as illustrated in FIG. 2. Eachadjustment element 24 can be supported relative to the cutter body 12 bya retaining element that can be inserted in an axial direction relativeto the cutter body 12 into a retaining element slot in the cutter body12 and further into a retaining element hole in the adjustment element24. The retaining element functions to hold the adjustment element 24 inplace against the centrifugal forces of milling cutter 10 whenperforming a milling operation. Suitable adjustment elements arecommercially available from Kennametal Inc. as Assembly Part Nos.479.116 and 479.100.

[0017] The adjustment element 24 has a tapered hole 24 a and a slot 24 bextending from the tapered hole 24 a to an edge 24 c of the adjustmentelement 24. A tapered screw 28 is threaded into a portion (not shown) ofthe adjustment element 24. Upon tightening the tapered screw 28 into thetapered hole 24 a, the slot 24 b in the adjustment element 24 expands,moving the cutting insert 18 in an axial direction.

[0018] The finishing ring 14 includes a ring of abrasive materialapplied on a first side or face 12 f of the cutter body 12. Thefinishing ring 14 comprises at least one abrasive surface, such as anabrasive surface made, for example, of aluminum oxide, diamond, cubicboron nitride (CBN), or other suitable abrasive material. The abrasivematerial forming the abrasive surface may be arranged randomly, in adefined pattern, as a single piece or formed of multiple discreteportions. The abrasive material forming the abrasive surface may beapplied to the cutter body by electroplating, brazing, gluing, or byother means well known in the art. For example, the abrasive may beplaced on the face of the cutter body, and a metal is electroplated ontothe face, successive layers being plated until the abrasive is fixed tothe face of the cutter body.

[0019] In an alternate embodiment, the abrasive surface may be bonded toa mesh material that is affixed to the cutter body 12. For a moredetailed discussion of a suitable abrasive surface reference is made toU.S. Pat. Nos. 6,478,831; 5,049,165; 5,190,568; 5,203,880; 5,380,390;5,791,330; 5,980,678; 5,092,910 and 4,925,457, incorporated herein byreference.

[0020] The abrasive surface may be formed as a random array ofparticles, e.g. FIG. 1, or the abrasive surface may be applied as auniform pattern of particles, e.g., FIG. 3.

[0021] When the spindle is rotated at a high speed by a rotatable drivesource (not shown), the cutter body 12 is rotated. As the milling cutter10 traverses a workpiece (not shown), the cutting edges 18 b of theinserts 18 mounted on the cutter body 12 cut the workpiece while theabrasive surface of the finishing ring 14 finishes the workpiece.

[0022] The cutting edges 18 b of the cutting inserts 18 may become wornor damaged, or may require replacement to meet a particular need. Thecutting edges 18 b can easily be changed simply by indexing the cuttinginsert to another cutting edge or by replacing the inserts 18 entirely.The cutting inserts 18 can easily be moved and the position of thecutting edges 18 b can easily be adjusted relative to the cutter body 12simply by adjusting the position of the adjustment element 24.

[0023] The finishing ring 14 of the milling cutter functions to grindthe workpiece. As stated above, the abrasive surface can be diamond,cubic boron nitride (CBN), or any other type of finishing media. Thepreferred finishing ring 14 does not contain any type of replaceableinsert. When the abrasive surface is worn, the finishing ring of thecutter body is resurfaced with new abrasive as previously described.

[0024] When the milling cutter 10 is used, the finishing ring 14projects axially from the cutter body 12 slightly farther than do thecutting inserts 18. The milling cutter 10 can perform both rough andfinish milling during a single operation or pass or can perform eitherrough milling and then finish milling during multiple operations orpasses. By adjusting the position of the cutting inserts 18 axiallyrelative to the cutter body 12, the amount of work performed by thefinishing ring 14 is adjusted. As the axial distance between the cuttingedges 18 b of the cutting inserts 18 is increased, the amount ofmaterial removed from the workpiece by the finishing ring 14 isincreased. It should be clearly understood by one of ordinary skill inthe art of the invention that the finishing ring is intended to remove aminimal amount of material to provide a smooth finish work piecesurface.

[0025] While this invention has been described with respect to severalpreferred embodiments, various modifications and additions will becomeapparent to persons of ordinary skill in the art. All such variations,modifications, and variations are intended to be encompassed within thescope of this patent, which is limited only by the claims appendedhereto.

What is claimed is:
 1. A milling cutter comprising: a cutter body havingat least two annular operational rings formed thereon, the at least twooperational rings including an outer ring formed about the periphery ofthe cutter body and at least one inner ring radially inward of the outerring, wherein the outer ring has at least one insert pocket and acutting insert secured in the insert pocket and the at least one innerring has an abrasive surface thereon.
 2. The milling cutter of claim 1,wherein the cutter body has a plurality of insert pockets about theperiphery include the at least one insert pocket and a cutting insert issecured in each of the insert pockets.
 3. The milling cutter of claim 1,wherein the finish ring is concentric with the periphery of the cutterbody.
 4. The milling cutter of claim 1, wherein the cutting insertperforms a rough milling operation and the abrasive material performs afinish milling operation.
 5. The milling cutter of claim 1, wherein thecutting insert has a cutting edge tipped with a material suitable forremoving material from a workpiece.
 6. The milling cutter of claim 1,wherein the cutting insert is adjustable relative to the cutter body. 7.The milling cutter of claim 1, further comprising an adjustment elementsupported relative to the cutter body and adjustable in an axialdirection relative to the cutter body to move the cutting insert in anaxial direction relative to the cutter body.
 8. The milling cutter ofclaim 1, wherein the adjustment element has a tapered hole and a slotextending from the tapered hole to an edge of the adjustment element,the tapered screw being adapted to be tightening into the tapered holeto expand the slot and the adjustment element to move the cutting insertin an axial direction.
 9. The milling cutter of claim 1, wherein theabrasive surface is formed of an abrasive material comprising aluminumoxide.
 10. The milling cutter of claim 1, wherein the abrasive surfaceis formed of an abrasive material comprising diamond.
 11. The millingcutter of claim 1, wherein the abrasive surface is formed of an abrasivematerial comprising cubic boron nitride.
 12. The milling cutter of claim1, wherein the abrasive surface is formed of a randomly arrangedabrasive material.
 13. The milling cutter of claim 12, wherein theabrasive surface is formed of an abrasive material arranged in apattern.
 14. The milling cutter of claim 1, wherein the abrasive surfaceis formed of an abrasive material bonded to a mesh material that isaffixed to the cutter body.
 15. The milling cutter of claim 1, whereinthe abrasive surface is electroplated to the cutter body.
 16. Themilling cutter of claim 1 wherein the abrasive surface is formed as asingle piece.
 17. The milling cutter of claim 1 wherein the abrasivesurface is formed of multiple discrete portions.
 18. The milling cutterof claim 1 wherein the cutting insert is a ceramic cutting insert. 19.The milling cutter of claim 1 wherein the cutting insert is a cementedcarbide cutting insert.
 20. The milling cutter of claim 1 wherein thecutting insert is a PCD tipped cutting insert.
 21. The milling cutter ofclaim 1 wherein the cutting insert is a PCBN tipped cutting insert.